Cathode ray tube



April 2, 1940. M. KNOLL -ET AL CATHODE RAY TUBE- Filed March 14, 1956 INVENTOR MAX KNOLL AND JOHCHIM S LOEMILCH BY 7 ATTb W RNEY Patented Apr. 2, 1940 UNITED STATES;

OATHODE RAY TUBE Max Knoll and Joachim Schloemilch, Berlin, Germany, assignors to Teleiunkcn Gesellschaft fiir Drahtlose Telegraphic m. b. 11., Berlin, Germany, a corporation of Germany Application March 14, 1936, Serial No. 68,968 I In Germany March 14, 1935 2 Claims.

The present invention is concerned with the idea to use, in a. lamp panel designed for television re-creation, in other words, in an ar-' rangement in which a multiplicity of lamps is uniformly distributed over a surface or panel, and in which these lamps are operated and controlled in accordance with the brightness or luminosity of a given picture element or unit, lamps of the cathode-ray type furnished with a fluorescent screen. Lamps of this type offer this advantage over glow-discharge or glow-tubes previously suggested for the same object that the brightness or luminosity thereof is controllable in the simplest possible way, and that the fluorescent substance exhibits phosphorescence or after-glow during intermissions, with the result that the television picture is subject to less flicker'than is truein the case of glow-tubes. Another merit is that they are far less sensitive to variations of the gas pressure than glow-tubes, and that, by choosing a fluorescent substance suitable therefor, they are adapted to produce television pictures also in natural or. white color.

An exemplified formof construction of a cathode-ray or electron-ray tube of the kind here disclosed shallbe described in what follows by referenceto the annexed drawing showing a schematic view thereof. This exemplified embodiment at the same time will make evident a numher of advantageous details and features in the construction of the tube. e I

Referring tothe single figure of the drawing,

i0 is a glass vessel in theisquash or press ll of which are sealed two lead-ins l2 and I3 for the cathode l4, and furthermore a lead l5 for the control grid It. The fluorescent screen is placed upon the topwall of the glass vessel [0, to be more precise, at the place marked ll. I8 is a conducting coat or deposit, say, consisting of conl0 ductive carbon.(so-called retort graphite or carbon) which acts as the anode, and which is connected with the outside by way of a distinct seal I9. s I

In addition to its function as a transducer de- 4 signed to convert electrical energy into luminous energy, the cathode-ray tube plays also the part of an amplifier tube. Impressed upon the lead 15 of the control grid It, by means of a suitable switch, are the potentials coming in from the transmitter station, if desired, after input amplification. This change-over switch, either in .the sequence of the picture elements inside one line, may connect each individual lamp or tube 55 with the transmission line or circuit and then produce disconnection; or else to the first, sec-,-

ond, third, etc., picture units or elementary areas of all lines, a distinct transmission line may be co-ordinated, and by the change-over switch consecutively each individual picture line may be '5 connected.

The control grid l6, as shown in the drawing, is surrounded by a sheet metal disk 20 which extends close to the glass vessel. This disk has the purpose of precluding a discharge between 10 cathode and anode in away by-passing or circumventing the control grid. The said disk as shown in the drawing, could also be made pot-shaped, and in that case even higher potentials may be used at the anode without a discharge that will 15 circumvent the grid having to be feared. The same object is served by two sheets 2 I, 22 mounted on the heated cathode turnedaway from the grid.

Upon the top of the control grid or the shield- 20 ing surface 20 turned towards the anode is a tubular body 23. The effect of the latter is to considerably diminish the controllance of the anode across the control grid with the consequence that a comparatively small change in the grid voltage 25 will sufiice in order that the fluorescence spot may be changed all the way from maximum to minimum brightness. The axial length of the tubular .body 23 may be so proportioned that. the fiuorescent spot will sweep'and cover the fluorescent 30 screen I! throughout its entire area.

What is claimed: I

l. A cathode ray tube comprising an envelope containing a cathode, a modulating electrode, a shield electrode substantially embracing said 5 cathode and modulating electrode, said. shield electrode comprising two abutting substantially cylindrical sections, said modulating electrode being positioned substantially in the plane'of abutment of said cylindrical members comprising the 40 shield electrode, fluorescing means positioned substantially at the end of the envelope of the tube remote from the cathode, and anode means interposed between said fiuorescing means and said modulating electrode, said anode means being positioned so that said shield electrode is interposed between the modulating electrode and the anode means. i

2. Apparatus in accordance with claim 1 where in there is provided, in addition, a pair of metallic sheet members positioned on the side of the cathode remote from the modulating electrode.

MAX KNOLL. JOACHIM SCHLOEMILCH. 

